The need for increased RF spectrum access for wireless broadband applications continues within the commercial and government user domains. Since the usable RF spectrum is fully allocated, the only options available are to: a) increase the efficiency of current spectrum uses; b) re-purpose spectrum to higher value uses; or c) institute spectrum sharing. While the FCC has a database of authorized, licensed spectrum users, the ultimate success of any of these options depends on knowledge of actual RF spectrum utilization in time, frequency, and space. Studies have shown that although the spectrum is fully allocated, the actual occupancy at a given time and place may be low, which is indicative of low spectral efficiency.
There is a need to obtain mappings and models of the temporal and spatial variations of the RF environment with sufficiently high fidelity to estimate, characterize, and model spectrum utilization, actual multi-site RF measurements. With the infrastructure to collect and access spectrum data in place, it is necessary to 1) provide new methods for analyzing, modeling, and visualizing the resulting large, multi-dimensional information base; and 2) model spectrum activity to test the feasibility of spectrum sharing in candidate bands in order to facilitate decision-making and innovation in spectrum repurposing and sharing. To facilitate both of these analysis goals in any specific band, the entire list of signals and holes needs to be extracted and modeled. The frequency allocations of some of the signals are sometimes stored in a repository, such as the TV white space spectrum database. For such signals, the analysis of measured spectrum data is easier. However, this is frequently not the case, especially when it comes to analyzing wideband measurements that can span multiple frequency bands. In a majority of cases, the positions of the signals are not known by the spectrum sensor and the frequency locations of the signals and holes themselves need to be extracted first.